Effect of Nitrogen Flushing on the Production of Proteinase by Psychrotrophic Bacteria in Raw Milk

Murray, Shane L.; Kwan, K.K.H.; Skura, B.J.; McKellar, R.C.

doi:10.1111/j.1365-2621.1983.tb09183.x

Cited by 23 publications

(28 citation statements)

References 19 publications

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“…These results were in contradiction to those obtained by some other authors [10,14]. During the entire incubation period, the Pseudomonadaceae percentage was greater in the milk under the gaseous atmosphere.…”

Section: Effect Of a Mixture Of 50 % Co 2 And 50 % N 2 On The Differecontrasting

confidence: 99%

“…For a long time carbon dioxide has been known to inhibit food spoilage bacteria [3, 4, 6±9] and nitrogen was suggested for the deaeration of raw milk as a possible means of spoilage pre-vention [14,18]. For a long time carbon dioxide has been known to inhibit food spoilage bacteria [3, 4, 6±9] and nitrogen was suggested for the deaeration of raw milk as a possible means of spoilage pre-vention [14,18].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Modified Atmospheres on the Growth and Extracellular Enzyme Activities of Psychrotrophs in Raw Milk

2005

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The conservation of food products within a controlled atmosphere is efficient in packaging. To extend the cold storage of raw milk, the effects of five gas atmospheres enriched with carbon dioxide and nitrogen were investigated. Treated and control milk were stored at 7 °C for 10 days and analyzed for microbial counts, pH, proteolysis and lipolysis. The addition of CO2, N2, or their mixture had a significant inhibitory effect on psychrotrophic growth. The generation times of these microorganisms were significantly longer in treated milk, particularly for yeasts where they amounted to 16.63 h. The maximum inhibition was observed when a gas mixture of 50 % CO2 and 50 % N2 was used. As a result, psychrotrophic growth was affected to 98 % whereas this inhibition did not exceed 78 % when CO2 and 41 % N2 were applied. Milk treatment under the conditions of 50 % CO2 and 50 % N2 gave significantly lower counts for all groups of psychrotrophs being more efficient against Enterobacteriaceae with 99.5 % of inhibition. Storage of raw milk under the tested atmospheres had a different effect on extracellular enzyme productions. Significant decreases in protease and lipase activities were observed during the storage at 7 °C. These enzyme activities were not detectable with pure CO2 and a 50 % CO2 and 50 % N2 mixture. N2 has shown to be the less efficient treatment against lipases (65 %) and proteases (95 %). With regard to growth, the course of the pH and the protease and lipase activities, the tested gas mixture of 50 % CO2 and 50 % N2 was more suitable for extending the shelf life of raw milk.

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Section: Effect Of a Mixture Of 50 % Co 2 And 50 % N 2 On The Differecontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Modified Atmospheres on the Growth and Extracellular Enzyme Activities of Psychrotrophs in Raw Milk

2005

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“…Two studies examined the use of N 2 gas to prevent bacterial growth in raw milk that was kept in a “closed system” (Murray et al, 1983; Dechemi et al, 2005). By considering an “open system,” both culture-dependent investigations and DNA barcoding studies revealed that no pathogen, no spoilage bacteria or any anaerobe was clearly advantaged by the N 2 gas flushing treatment when it was applied to raw milk at the laboratory scale, despite the fact that 10 4 - fold lower bacterial counts differentiated the N 2 -flushed from non-flushed cold-stored raw milk samples (Munsch-Alatossava et al, 2010a,b; Gschwendtner et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

N2 Gas Flushing Limits the Rise of Antibiotic-Resistant Bacteria in Bovine Raw Milk during Cold Storage

et al. 2017

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Antibiotic resistance has been noted to be a major and increasing human health issue. Cold storage of raw milk promotes the thriving of psychrotrophic/psychrotolerant bacteria, which are well known for their ability to produce enzymes that are frequently heat stable. However, these bacteria also carry antibiotic resistance (AR) features. In places, where no cold chain facilities are available and despite existing recommendations numerous adulterants, including antibiotics, are added to raw milk. Previously, N2 gas flushing showed real potential for hindering bacterial growth in raw milk at a storage temperature ranging from 6 to 25°C. Here, the ability of N2 gas (N) to tackle antibiotic- resistant bacteria was tested and compared to that of the activated lactoperoxidase system (HT) for three raw milk samples that were stored at 6°C for 7 days. To that end, the mesophiles and psychrotrophs that were resistant to gentamycin (G), ceftazidime (Ce), levofloxacin (L), and trimethoprim-sulfamethoxazole (TS) were enumerated. For the log10 ratio (which is defined as the bacterial counts from a certain condition divided by the counts on the corresponding control), classical Analyses of Variance (ANOVA) was performed, followed by a mean comparison with the Ryan-Einot-Gabriel-Welsch multiple range test (REGWQ). If the storage “time” factor was the major determinant of the recorded effects, cold storage alone or in combination with HT or with N promoted a sample-dependent response in consideration of the AR levels. The efficiency of N in limiting the increase in AR was highest for fresh raw milk and was judged to be equivalent to that of HT for one sample and superior to that of HT for the two other samples; moreover, compared to HT, N seemed to favor a more diverse community at 6°C that was less heavily loaded with antibiotic multi-resistance features. Our results imply that N2 gas flushing could strengthen cold storage of raw milk by tackling the bacterial spoilage potential while simultaneously hindering the increase of bacteria carrying antibiotic resistance/multi-resistance features.

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“…However, the treatments also promote the acidification of milk or the modification of its sensory properties. Two studies investigated the use of nitrogen (N 2 ), considered an inert gas, to inhibit bacterial growth and the spoilage potential present in raw milk [24,25]. Both studies investigated a “closed system” with no possibility of gas exchange between the milk flasks and the environment.…”

Section: Introductionmentioning

confidence: 99%

Potential of Nitrogen Gas (N2) Flushing to Extend the Shelf Life of Cold Stored Pasteurised Milk

Munsch-Alatossava

Ghafar

Alatossava

2013

IJMS

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For different reasons, the amount of food loss for developing and developed countries is approximately equivalent. Altogether, these losses represent approximately 1/3 of the global food production. Significant amounts of pasteurised milk are lost due to bad smell and unpleasant taste. Currently, even under the best cold chain conditions, psychrotolerant spore-forming bacteria, some of which also harbour virulent factors, limit the shelf life of pasteurised milk. N2 gas-based flushing has recently been of interest for improving the quality of raw milk. Here, we evaluated the possibility of addressing bacterial growth in pasteurised milk during cold storage at 6 °C and 8 °C. Clearly, the treatments hindered bacterial growth, in a laboratory setting, when N2-treated milk were compared to the corresponding controls, which suggests that N2-flushing treatment constitutes a promising option to extend the shelf life of pasteurised milk.

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Effect of Nitrogen Flushing on the Production of Proteinase by Psychrotrophic Bacteria in Raw Milk

Cited by 23 publications

References 19 publications

Effect of Modified Atmospheres on the Growth and Extracellular Enzyme Activities of Psychrotrophs in Raw Milk

Effect of Modified Atmospheres on the Growth and Extracellular Enzyme Activities of Psychrotrophs in Raw Milk

N2 Gas Flushing Limits the Rise of Antibiotic-Resistant Bacteria in Bovine Raw Milk during Cold Storage

Potential of Nitrogen Gas (N2) Flushing to Extend the Shelf Life of Cold Stored Pasteurised Milk

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